support "login-shell" mode for local processes, and misc ssh/tool tidies
expose methods for extracting connection details from an SshMachineLocation, with tests,
particularly in dealing with private keys (needed e.g. to configure knife, which requires an unpasphrased key file generated)
chef server integration working, based on knife, as well as chef solo and auto-detect
whoops incomplete chef-hosted keys update, and removing dead code and unpermitted actions
(so that the keys as checked in are relatively safe, don't have quite as many permissions at chef-hosted as the one we almost checked in!)
add a way to run commands before invoking knife, needed where rvm is installed
new test for code review
Merge pull request #910 from ahgittin/feature/chef

feature/chef